diff --git a/apps/api/src/groups/module-grants.service.spec.ts b/apps/api/src/groups/module-grants.service.spec.ts
index f46dae5..de666fb 100644
--- a/apps/api/src/groups/module-grants.service.spec.ts
+++ b/apps/api/src/groups/module-grants.service.spec.ts
@@ -15,6 +15,7 @@ function makeFakePrisma() {
   const groups = new Map<string, any>();
   const users = new Map<string, any>();
   const memberships = new Map<string, Set<string>>(); // groupId -> Set<userId>
+  const membershipSources = new Map<string, string>(); // `${groupId}::${userId}` -> source
   const activations = new Map<string, any>(); // key: tenantId::moduleId
   const grants = new Map<string, any>();
   let grantCounter = 0;
@@ -47,10 +48,11 @@ function makeFakePrisma() {
     __seedUser(user: { id: string; tenantId: string }) {
       users.set(user.id, user);
     },
-    __seedMembership(groupId: string, userId: string) {
+    __seedMembership(groupId: string, userId: string, source: string = 'MANUAL') {
       const set = memberships.get(groupId) ?? new Set<string>();
       set.add(userId);
       memberships.set(groupId, set);
+      membershipSources.set(`${groupId}::${userId}`, source);
     },
     __seedActivation(a: {
       tenantId: string;
@@ -145,6 +147,25 @@ function makeFakePrisma() {
         return { count };
       },
     },
+    groupMembership: {
+      findMany: async ({ where }: any) => {
+        const userId = where.userId;
+        const tenantId = where.group.tenantId;
+        const rows: any[] = [];
+        for (const [groupId, memberSet] of memberships.entries()) {
+          if (!memberSet.has(userId)) continue;
+          const group = groups.get(groupId);
+          if (!group || group.tenantId !== tenantId) continue;
+          rows.push({
+            groupId,
+            userId,
+            source: membershipSources.get(`${groupId}::${userId}`) ?? 'MANUAL',
+            group: { id: group.id, name: group.name },
+          });
+        }
+        return rows;
+      },
+    },
   };
 }
 
@@ -383,13 +404,14 @@ describe('ModuleGrantsService.getUserAccess', () => {
 
     const result = await service.getUserAccess('t1', 'u1');
 
-    expect(result).toEqual([
+    expect(result.modules).toEqual([
       {
         module: { id: 'mod-1', category: 'ops', name: 'Modul Eins' },
         viaGroups: ['Gruppe A'],
         direct: false,
       },
     ]);
+    expect(result.groups).toEqual([{ id: 'g1', name: 'Gruppe A', source: 'MANUAL' }]);
   });
 
   it('adjacency: ein Direkt-Grant UND ein Gruppen-Grant auf dasselbe Modul erscheinen gleichzeitig, keiner verdrängt den anderen', async () => {
@@ -402,8 +424,8 @@ describe('ModuleGrantsService.getUserAccess', () => {
 
     const result = await service.getUserAccess('t1', 'u1');
 
-    expect(result[0].viaGroups).toEqual(['Gruppe A']);
-    expect(result[0].direct).toBe(true);
+    expect(result.modules[0].viaGroups).toEqual(['Gruppe A']);
+    expect(result.modules[0].direct).toBe(true);
   });
 
   it('wirft NotFoundException für eine userId aus einem anderen Mandanten', async () => {
@@ -416,6 +438,71 @@ describe('ModuleGrantsService.getUserAccess', () => {
       NotFoundException,
     );
   });
+
+  it('REGRESSION: Mitglied einer Gruppe ohne Modul-Freigabe bleibt sichtbar', async () => {
+    const prisma = makeFakePrisma();
+    seedBase(prisma);
+    prisma.__seedMembership('g1', 'u1');
+    // Bewusst KEIN Grant für g1 auf mod-1.
+    const service = new ModuleGrantsService(prisma as any);
+
+    const result = await service.getUserAccess('t1', 'u1');
+
+    expect(result.groups).toEqual([{ id: 'g1', name: 'Gruppe A', source: 'MANUAL' }]);
+    expect(result.modules.every((m: any) => m.viaGroups.length === 0)).toBe(true);
+  });
+
+  it('Cross-Tenant: eine Mitgliedschaft in einer Gruppe eines fremden Mandanten erscheint nicht in groups', async () => {
+    const prisma = makeFakePrisma();
+    seedBase(prisma);
+    prisma.__seedGroup({ id: 'g-foreign', tenantId: 't2', name: 'Fremde Gruppe' });
+    prisma.__seedMembership('g-foreign', 'u1');
+    const service = new ModuleGrantsService(prisma as any);
+
+    const result = await service.getUserAccess('t1', 'u1');
+
+    expect(result.groups).toEqual([]);
+  });
+
+  it('Herkunft: eine mit source LDAP geseedete Mitgliedschaft kommt mit source LDAP zurück', async () => {
+    const prisma = makeFakePrisma();
+    seedBase(prisma);
+    prisma.__seedMembership('g1', 'u1', 'LDAP');
+    const service = new ModuleGrantsService(prisma as any);
+
+    const result = await service.getUserAccess('t1', 'u1');
+
+    expect(result.groups).toEqual([{ id: 'g1', name: 'Gruppe A', source: 'LDAP' }]);
+  });
+
+  it('ohne aktives Modul im Mandanten: modules ist leer, groups trotzdem befüllt', async () => {
+    const prisma = makeFakePrisma();
+    prisma.__seedGroup({ id: 'g1', tenantId: 't1', name: 'Gruppe A' });
+    prisma.__seedUser({ id: 'u1', tenantId: 't1' });
+    // keine Activation geseedet
+    prisma.__seedMembership('g1', 'u1');
+    const service = new ModuleGrantsService(prisma as any);
+
+    const result = await service.getUserAccess('t1', 'u1');
+
+    expect(result.modules).toEqual([]);
+    expect(result.groups).toEqual([{ id: 'g1', name: 'Gruppe A', source: 'MANUAL' }]);
+  });
+
+  it('Sortierung: groups ist alphabetisch nach name stabil über wiederholte Aufrufe', async () => {
+    const prisma = makeFakePrisma();
+    seedBase(prisma);
+    prisma.__seedGroup({ id: 'g2', tenantId: 't1', name: 'Alpha' });
+    prisma.__seedMembership('g1', 'u1');
+    prisma.__seedMembership('g2', 'u1');
+    const service = new ModuleGrantsService(prisma as any);
+
+    const first = await service.getUserAccess('t1', 'u1');
+    const second = await service.getUserAccess('t1', 'u1');
+
+    expect(first.groups.map((g: any) => g.name)).toEqual(['Alpha', 'Gruppe A']);
+    expect(second.groups.map((g: any) => g.name)).toEqual(['Alpha', 'Gruppe A']);
+  });
 });
 
 describe('ModuleGrantsService — Logging (D-23)', () => {